High-quality, precisely-controlled capacitors are an integral part of many semiconductor devices. Capacitors are fabricated as part of a semiconductor circuit using Metal-Oxide-Silicon (MOS) technology or Metal-Insulator-Silicon (MIS) technology. One particular example of a semiconductor capacitor is in an application for an integrated circuit whose function is the conversion of analog signals to digital signals. In this circuit a series of capacitors are formed by placing an oxide, such as silicon oxide, over the semiconductor substrate and then fabricating an electrode over the oxide in order to form the capacitor.
Much effort has been spent in attempting to increase the capacitance of capacitors in semiconductor networks. In developing thin film capacitors, properties such as dielectric constant, loss factor, mechanical Q factor, resistivity, leakage current, breakdown field, and charge storage are extremely important. Improvement of these properties is critical in applications such as voltage variable capacitors (varactors) and bypass capacitors that are typically used in microwave and semiconductor device applications. Generally, crystalline films are used to manufacture these capacitors. One of the problems encountered in crystalline films is that the electrical conductivity may be enhanced by the increased electric field at crystal lattice boundaries or at the film-electrode contact interfaces, resulting in breakdown at a much lower voltage. In the area where the top electrode contacts the dielectric insulator, film defects or voids, and spaces between the grain boundaries will result in an increased loss factor (tangent delta). This also has the effect of lowering the breakdown field and charge storage.
Since crystalline films possess the sought-after high dielectric constant, it would be highly advantageous to develop a capacitor system that could employ a crystalline film and avoid the negative problems inherent due to the structure of crystalline films.